Introducer for a medication infusion set

ABSTRACT

An introducer is provided for introducing a cannula for subcutaneous administration of fluid into a patient. The fluid is generally a medication, for example, insulin. The cannula is in fluid communication with a fluid passageway surrounded by a projection on the cannula housing that includes one or more rail-like extensions acting as connection guides. The introducer includes an introducer needle and one or more guide arms that slide over the rail-like extensions to guide the needle into the self-sealing septum. The introducer includes one or more locking arms, with barbs at the end, to connect with one or more recesses that are provided in the cannula housing.

RELATED APPLICATIONS

This is a divisional application, which claims priority from U.S. patentapplication Ser. No. 11/003,225, filed Dec. 3, 2004, which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to an infusion set for subcutaneousdelivery of a selected medication or other fluid to a patient. Moreparticularly, this invention relates to an improved infusion set havinga cannula housing and a connector for connecting the cannula housing toa delivery device.

2. Description of Related Art

Infusion sets are typically used for delivering a selected medication orother fluid to a patient. Infusion sets may include a cannula, which maybe relatively soft and flexible. The cannula provides a transcutaneouspassageway to administer a medication or other fluid to a subcutaneoussite on a patient. The cannula generally attached to a cannula housing,which may be placed on the skin of the patient when the cannula isinserted. A connector attaches to the cannula housing to connect thecannula to the fluid delivery system. The fluid delivery system isgenerally placed in fluid communication with the connector by way of alength of infusion tubing. Examples of fluid delivery systems are shownin U.S. Pat. Nos. 4,562,751, 4,685,903, 5,080,653, 5,097,122, which areherein incorporated by reference.

Infusion sets of the type described above are generally used to delivermedication, such as insulin, to a patient over an extended period oftime. The infusion sets usually are adapted to rest on the skin of thepatient. The cannula housing may remain on the patient's skin forseveral days, and the patient may disconnect the connector whenperforming certain activities, like showering. Because a patient changesinfusion sets fairly frequently, it is beneficial to have an infusionset that is easy to insert, easy to connect properly, and easy to removeand dispose of.

An infusion set of the above type is described in U.S. Pat. No.5,522,803. The infusion set comprises a cannula housing with a cannulaand a needle holder to be connected to the cannula housing. The cannulahousing includes two guide openings and two locking openings withshoulders for engaging barbs on locking pins of the needle holder. Theneedle holder includes guide pins that co-operate with the guideopenings on the cannula housing. The needle on the needle holder isguided by the guide pins into the cannula housing so that the needlepenetrates a membrane at the inlet of a fluid passageway of the cannulahousing. The fluid passageway is in fluid communication with thecannula. Thus, when the needle penetrates the membrane, the fluid mayflow through the connector into the cannula housing and then into thepatient. The guide pins must be guided carefully into the guideopenings, as the guide openings surround the pins on all four sides whenthe cannula housing and needle holder are guided together.

Another infusion set of the above type is described in U.S. Pat. No.6,302,866. The infusion set comprises a cannula housing with acylindrical extension and a needle holder with a guide sleeve thatclosely slides over the cylindrical extension. The connection must bedone carefully, because the cylindrical extension fits closely into theguide sleeve. The guide sleeve surrounds a connecting needle that isguided into the passageway of the cylindrical extension. The passagewayin the cylindrical extension is in fluid communication with the cannulaand has a septum at its inlet that is pierced by the connecting needle.Once the septum is pierced, fluid can flow from an infusion devicethrough the needle holder into the cannula housing and then into thepatient.

BRIEF SUMMARY OF THE INVENTION

In accordance with the invention, an infusion set is provided for use indelivering fluid through a cannula to a selected subcutaneous infusionsite on a patient. The fluid is generally a medication, for example,insulin. The cannula is a soft and flexible cannula and is supported bya cannula housing. The cannula housing also includes a fluid passagewayin fluid communication with the cannula. At one end of the fluidpassageway is a self-sealing septum. The fluid passageway is surroundedby a projection on the cannula housing that includes one or morerail-like extensions acting as connection guides. The rail-likeextensions may be substantially triangular or otherwise suitably shapedto act as guides. The cannula housing also includes a base that restsupon a patient's skin when the cannula is inserted into the skin.

The infusion set also includes a connector that connects the cannulahousing to fluid tubing that allows fluid to flow from a fluid source,which may be a fluid delivery system, such as an infusion pump, throughthe connector to the cannula housing and through the cannula into thepatient. The connector includes a connecting needle that is mountedthereon to pierce the self-sealing septum on the cannula housing toallow flow of fluid through the needle into the fluid passageway. Theconnecting needle is in fluid communication with the fluid tubing. Theconnector also includes one or more guide arms that slide over therail-like extensions to guide the needle into the self-sealing septum.The connector includes one or more locking arms, with barbs at the end,to connect with one or more recesses that are provided in the cannulahousing. Once the barbs are pushed into the recesses, the connector isessentially locked in place with respect to the cannula housing. Theconnector is preferably reversible so that it may be connected to thecannula housing regardless of which side is up.

The cannula housing is inserted into the skin using an introducer. Theintroducer has the same guide arms and locking arms as the connector. Itincludes an introducing needle that passes through the self-sealingseptum and fluid passageway of the cannula housing and into the cannula.When connected to the cannula housing, the tip of the introducing needleis outside the cannula.

A method of delivery of a fluid is provided comprising positioning acannula housing according to the invention at an infusion site on apatient and engaging the cannula housing with a connector according tothe invention. The positioning of the cannula housing may include usingan introducer according to the invention to pierce the skin of thepatient, and removing the introducer from the cannula housing once thecannula housing is positioned on the infusion site.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention will be made withreference to the accompanying drawings, wherein like numerals designatecorresponding parts in the figures.

FIG. 1 is a perspective view of a cannula housing and connector inconnected form in accordance with an embodiment of the invention

FIG. 1A is a top view of a cannula housing and connector in connectedform in accordance with an embodiment of the invention.

FIG. 2 is perspective view of a cannula housing, connector, introducer,and internal components in accordance with an embodiment of theinvention in an exploded view.

FIG. 3 is a perspective view of a cannula housing in accordance with anembodiment of the invention.

FIG. 4 is a perspective view of a connector in accordance with anembodiment of the invention.

FIG. 5 is a perspective view of an introducer in accordance with anembodiment of the invention.

FIG. 6 is a horizontal sectional view of a cannula housing and connectorin connected form in accordance with an embodiment of the invention.

FIG. 7 is a perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

FIG. 8 is a perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

FIG. 9 is a perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

FIG. 10 is a perspective view of a cannula housing and connector inseparated form in accordance with an embodiment of the invention.

FIG. 11 is a top and a bottom perspective view of a cannula housing andconnector in separated form in accordance with an embodiment of theinvention.

FIG. 12 is a top perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

FIG. 13 is a perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

FIG. 14 is a top perspective view of a cannula housing and introducer inseparated form in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof and which illustrate severalembodiments of the present invention. It is understood that otherembodiments may be utilized and structural and operational changes maybe made without departing from the scope of the present invention.

As shown in FIGS. 1-3, the infusion set comprises a cannula housing 100and a connector 120. The cannula housing 100 carries a soft and flexiblecannula 200. The cannula 200 may be tapered at the end. Any flexibletubing may be used for the cannula, provided that is biocompatible andinsulin compatible. For example, but without limitation, the cannula 200may be composed of polytetrafluoroethylene (PTFE) or fluorinatedethylene propylene (FEP). The cannula housing 100 has a base 220 thatrests upon the patient's skin when the cannula 200 is inserted into thepatient. The base 220 may be attached to the patient's skin, for exampleby an adhesive patch. Although the base 220 is shown as at leastpartially circular in nature, it may be square, rectangular or any othershape that is desired. A projection 240 of the cannula housing 100surrounds a fluid passageway (not shown) that is in fluid communicationwith the cannula 200. At the end of the fluid passageway opposite thecannula is a septum 295. This may be a self-sealing septum, for examplea substantially barrel-shaped, such as a beer-barrel shaped,self-sealing septum. The septum may also be substantially shaped like adisc or a ball, or any other preferable shape.

The projection 240 is generally at least partially attached along itslength to the base 220. However, the projection 240 may be entirelyseparate from the base 220 along its length, allowing a space betweenthe projection 240 and the base 220. The end of the projection 240opposite the end with the septum 295 would still be attached toremainder of the cannula housing 100, such that the cannula housing 100is still only one integral piece. The base 220 may also have a groove260 cut into it to allow for a higher projection without the need forthe entire cannula housing 100 to be taller. The projection 240 may havea relatively flat top, which can also reduce the height of the cannulahousing 100 and of the infusion set and can reduce the overall volume ofthe infusion set. When the infusion set is thinner, it can have a lowerprofile and be less noticeable.

The two sides of the projection 240 on the cannula housing 100 arerail-like extensions or guide rails 242 and 244. These guide rails 242and 244 may be substantially triangular, as shown, but they may beshaped in any other configuration that allows for guiding of theconnector 120 onto the cannula housing 100. For example, they could berectangular or peg-shaped. At the side of the cannula housing 100 nearthe cannula 200, there are two recesses 270 and 272 formed to receivebarbs that are on locking arms of the connector. These guide rails arevisible to the user, making the infusion set easier to connect.Additionally, the base of the cannula housing assists in guiding theneedle, acting as a bottom boundary for a connector. The cannula ispreferably angled so that the cannula is inserted into the skin at anangle. The fluid passageway and connector fluid passageway may each besimilarly angled. If both are angled to match the cannula, the passageof fluid will be one straight line from the point at which the fluidenters the connector until the end of the cannula, where the fluidenters the patient's body.

As shown in FIGS. 1, 2 and 4, the connector 120 connects the cannulahousing 100 to fluid tubing 300, which allows fluid to flow from a fluidsource, which may be a fluid delivery system, such as an infusion pump,to the connector 120. The connector 120 includes a connecting needle320, which is in fluid communication with the fluid tubing 300. Insidethe connector 120, a connector fluid passageway allows the connectingneedle 320 to be in fluid communication with the fluid tubing 300. Theconnector 120 has two locking arms 340 and 342, with barbs 341 and 343on each that are received by the recesses 270 and 272 on the cannulahousing 100. There may be grips on one or more edges of the locking arms340 and 342 for facilitating grasping by the user. When the barbs 341and 343 are engaged with the recesses 270 and 272, the connector 120 isessentially locked into the cannula housing 100. To disconnect theconnector 120 from the cannula housing 120, the user pushes the lockingarms 340 and 342 toward each other and releases the barbs 341 and 343from the recesses 270 and 272. Alternatively, the locking arms 340 and342 may be formed as levers, which would allow the ends of the lockingarms to release outwardly when the user pressed on the ends opposite thebarbs. It is also possible to remove one of the locking arms entirely orto replace one locking arm with an arm that does not latch or lock intothe cannula housing. In such an embodiment, only one locking arm wouldlock into the cannula housing. As another alternative, the locking armsmay have alternative locking structures to barbs, such as clips or otherconnecting pieces.

On either side of the needle 320 on the connector 120 are guide arms 350and 352. The guide arms 350 and 352 extend alongside and past the needle320. Because the guide arms 350 and 352 extend past the needle 320, itis difficult for the user to be injured by, or to injure, the needle 320when the connector 120 is separated from the cannula housing 120. Theguide arms 350 and 352 have indentations 351 and 353 that match theguide rails 242 and 244 of the projection 240 of the connector 120. Forexample, if the guide rails 242 and 244 are triangular in shape, theguide arms 350 and 352 will have triangular indentations. When the userconnects the connector 120 to the cannula housing 100, the guide arms350 and 352 slide along the projection 240, guiding the needle 320 intothe fluid passageway of the cannula housing 100.

The connector is preferably symmetrical, so that it is reversible andmay be placed into the connector with either of its top or bottom facingupward. If the connector is symmetrical, the patient does not have toworry about which way to place the connector. This will allow forquicker and easier connection.

The cannula housing may be adhered to the patient's skin by an adhesive.The adhesive may be on a patch that is attached to the base of thecannula housing. In one embodiment, as shown in FIGS. 1, 1A and 2, theadhesive is covered with a one or more piece liner 160 (or 165 in FIG.1A) that the patient removes to release the adhesive side. The liner 160protects the adhesive from being removed or from attaching to anythingelse until the patient wishes to use the infusion set. The liner canalso keep the adhesive layer relatively sterile. As shown in FIGS. 1 and2, the adhesive may be on a flat patch that is attached to the base.Alternatively, the adhesive may be folded, as shown in FIG. 1A. In thefolded configuration, the patient removes a small liner piece from theunfolded portion of the patch. The patient then inserts the cannula intothe skin. Afterward, the user pulls the liner off of the folded portionof the patch, allowing it to lie flat on the user's skin. In eitherconfiguration, the patch may be colored, patterned, or a combination ofboth. In the folded configuration, the small liner piece from theunfolded portion may have a color and/or pattern that is different fromthe color and/or pattern on the folded portion to more easilydifferentiate between the two liners.

To insert the cannula into the patient, an introducer may be used. Asshown in FIGS. 2 and 5, the introducer 140 has guide arms 450 and 452and locking arms 440 and 442 that are shaped the same as those on theconnector 120. However, the introducer needle 400 is much longer thanthe needle on the connector. The introducer needle 400 is long enoughthat when the introducer 140 is connected to the cannula housing 100,the tip of the introducer needle 400 extends beyond the cannula 200. Theintroducer needle 400 may be affixed to the introducer 140 by a UV orother type of adhesive, by welding, by a molding process, or by anyother suitable process. To insert the cannula 200 into the patient, theuser grips the joined introducer 140 and cannula housing 100 and insertsthe tip of the introducer needle 400 into the patient. The introducerneedle 400 and cannula 200 are pushed into the patient, so that thecannula 200 is almost entirely under the skin of the patient. Thecannula housing 100 is preferably affixed to the patient's outer skin,and the introducer 140 is unlocked and removed from the cannula housing100. The connector 120 can then be inserted and locked into the cannulahousing 100 so that fluid may be infused into the patient. In furtherembodiments, rubber grips may be overmolded onto the grips of theintroducer and/or the connector to improve ability to grasp theintroducer and/or connector. In addition, rubber overmold may be addedto the cannula housing 100 to improve the user's ability to grasp thepart during removal of the introducer 140 or connector 120.

The cannula housing 100 can be packaged connected to the introducer. Toprotect the patient from injury from the needle, a needle guard maycover the introducer needle, which extends beyond the cannula. Theneedle guard may be a small plastic tube that covers the needle and someor all of the cannula. If a small plastic tube is used as a needleguard, it may be colored so that it is easily visible. Thus, the patienteasily would be able to see if the needle guard is in place. The smallplastic tube may have only holes at each end of the tube. Alternatively,it may be slit down the side for ease of removal and replacement. A slitguard may reduce damage to the cannula 200 caused by attempting to slidethe small plastic tube onto the needle and cannula. A larger needlecover may also be used. The larger needle cover may connect or snap tothe cannula housing. It may also act as a cover for the introducer afterinsertion of the cannula, when the introducer is removed from thecannula housing.

The cannula housing may be made out of a plastic, such as an acrylic orpolypropylene or polycarbonate. A polycarbonate cannula housing may betransparent, so that the patient can see whether any bubbles are presentin the fluid passageway. The connector may also be made out of aplastic, such as an acrylic or polypropylene or polycarbonate. As in thecannula housing, a polycarbonate connector may be transparent, so thatthe patient can see whether any bubbles are present in the connectorfluid passageway. The plastics used for the cannula housing and theconnector should be compatible with the medication or fluid selected fordelivery through these parts and should pass the required biologicaltests for skin contact.

The patch or infusion set itself may be time-sensitive, to indicate tothe patient when it is time to remove the infusion set. A time-sensitiveindicator may be chemical, mechanical, or electrical. The patch itself,a portion of the patch, the infusion set, or a portion of the infusionset may contain an ink that changes color or appearance with passage oftime. An infusion set is typically used for a minimum of 3 days, but maybe adapted to be used for any predetermined period of time. Similarly,the time-sensitive indicator may be designed to be used for anypredetermined period of time. Alternatively, a different colored patchmay be used for a different day of the week, meaning the first and/orlast day for the infusion set, so that the user will easily know when tochange the infusion set. For example, if the color red means the firstday for the set is Monday and the last day is set for Wednesday, theuser will know to insert the infusion set on Monday and to remove it onWednesday. Graphics and other designs may also be printed on thepatches.

FIG. 6 is a cutaway view of the infusion set comprising the cannulahousing 100 and the connector 120. The connecting needle 320 has piercedthe substantially beer-barrel shaped septum 295 to allow flow from thefluid tubing 300 into the fluid passageway 380. At the end of thecannula housing 100, past the beer-barrel shaped septum 295 there may bea washer 290, which can assist in holding the beer-barrel shaped septum295 in place and provide compression to the septum to create a seal. Thewasher 290 may be made of suitable materials, for example metal orplastic. The washer 390 may be welded to the connector to retain theseptum 295. A needle guide 395 may be used to align the needle with thefluid passageway 380. The needle guide 395 may be a metal guide or aplastic guide. To seal the needle guide 395 into the cannula housing100, one or more sealing points may be used.

To aid in insertion of the cannula, an injector tool may be used.Injector tools may be of the type described in PCT Publication No. WO02/100457 A2, entitled “Insertion Device for an Insertion Set and Methodof Using Same,” published Dec. 19, 2002, which is herein incorporated byreference. Injector tools are useful for patients who are reluctant orhesitant to pierce their own skin with a medical needle. The injectortool is designed to place the needle through the skin at a selectedinsertion angle and with a controlled force and speed of insertion toensure proper placement with minimal discomfort.

Without being limited, several other embodiments of infusion setscomprising cannula housings and connectors, and the correspondingintroducers, are described below. Because the structure of the portionof the introducer that mates with the cannula housing is the same as theportion of the connector that mates with the cannula housing, eachembodiment is described with respect to the introducer and cannulahousing or with respect to the connector and cannula housing. It isintended that the connector and/or introducer not described has the samemating structure as the element that is described.

As shown in FIG. 7, in one embodiment the introducer 140 does not haveguide arms that are separate from locking arms. Instead, the lockingarms 640 and 642 each include barbs (641 and 643) and guide rails (644and 645). The guide rails 644 and 645 slide into recesses 650 and 652 onthe cannula housing 100.

As shown in FIG. 8, in one embodiment the introducer 140 does not haveguide arms. The locking arms 740 and 742 with barbs 741 and 743 are asdescribed with respect to FIGS. 1-4. The introducer 140 includes a guidesheath 750 that closely slides over the projection 760 on the cannulahousing 120 that surrounds the fluid passageway (not shown). The guidesheath 750 is also guided by two guide rails 772 and 774 that containindentations matching the exterior of the guide sheath 750. Thus theguide sheath closely fits in between the projection 760 and the guiderails 772 and 774 to guide the introducer 140 and introducer needle (notshown) into the cannula housing 100.

As shown in FIG. 9, in one embodiment the introducer 140 does not haveguide arms. The locking arms 840 and 842 with barbs 841 and 843 are asdescribed with respect to FIGS. 1-4. The introducer 140 has a dove tail850 that mates with a cut-out 860 to guide the introducer 140 andintroducer needle (not shown) into the cannula housing 100.

As shown in FIG. 10, in one embodiment the connector 120 does not haveguide arms. The locking arms 940 and 942 with barbs 941 and 943 are asdescribed with respect to FIGS. 1-4. The connector 120 also includes aguide pin 950 that can mate with one of two guide openings 960, 962 onthe cannula housing 100. As in other embodiments, the cannula housing100 and connector 120 are preferably symmetrical, aside from the oneguide pin 950, so that the user may insert the connector 120 into thecannula housing 100 regardless of which side is up. Thus, whether theone guide pin 950 will slide into a particular guide opening, 960 or962, is dependent upon which way the connector 120 is placed withrespect to the cannula housing 100. But it will be equally easy to slidethe connector 120 into the cannula housing 100 in each placement.

As shown in FIG. 11, in one embodiment the connector 120 does not haveguide arms. Instead, the locking arms 1040 and 1042 each include barbs(1041 and 1043) and guide rails (1044 and 1045). The guide rails 1044and 1045 slide into recesses 1050 and 1052 on the cannula housing 100.Additionally, this embodiment may include underside rails 1053 and 1054on the cannula housing 100, which slide alongside matching undersideguide features 1055 and 1056 on the locking arms 1040 and 1042. Thus,the connector 120 is guided into the cannula housing 100 by bothcombinations of the guide rails 1044, 1045 and recesses 1050, 1052 andthe underside rails 1053, 1054 and underside guide features 1055, 1056.

As shown in FIGS. 12-14, in several embodiments, the connector 120 doesnot have guide arms. The locking arms (1140 and 1142, 1240 and 1242, and1340 and 1342) with barbs (1141 and 1143, 1241 and 1243, and 1341 and1343) are as described with respect to FIGS. 1-4. The connector 120includes a partial guide sheath which may be a half box sheath 1150, anincomplete box sheath 1250, or an incomplete oval sheath 1350. The guidesheath (1150, 1250, or 1350) closely slides over the projection (1160,1260, or 1360) on the cannula housing 120 that surrounds the fluidpassageway (not shown). The guide sheath (1150, 1250, or 1350) is alsoguided by two guide rails (1172 and 1174, 1272 and 1274, and 1372 and1374) that mate with the exterior of the guide sheath (1150, 1250, or1350). Thus the guide sheath closely fits in between the projection andthe guide rails to guide the connector 120 and connector needle (notshown) into the cannula housing 100.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1. An introducer to introduce a cannula for subcutaneous administrationof fluid into a patient, the introducer comprising: an introducerneedle; a first arm having a first groove adapted to slide on a firstguide rail of a cannula housing and a second arm having a second grooveadapted to slide on a second guide rail of the cannula housing, whereinthe cannula housing includes a cannula mounted thereon and fluidcommunication with a fluid passageway inside a projection, and whereinthe first guide rail and the second guide rail are each on theprojection.
 2. The introducer of claim 1, wherein the first grooveextends along substantially all of the length of the first arm.
 3. Theintroducer of claim 1, further comprising a first locking arm, whereinthe first locking arm includes a first barb adapted to be received by afirst recess in the cannula housing.
 4. The introducer of claim 3,further comprising a second locking arm, wherein the second locking armincludes a second barb adapted to be received by a second recess in thecannula housing.
 5. The introducer of claim 3, wherein the locking armincludes a grip.
 6. The introducer of claim 1, wherein the first guiderail and the second guide rail are each substantially triangular shaped.7. The introducer of claim 1, wherein the fluid is insulin.
 8. Theintroducer of claim 1, wherein the introducer is composed of acrylic. 9.The introducer of claim 1, wherein the introducer is composed ofpolypropylene.
 10. The introducer of claim 1, wherein the introducer iscomposed of polycarbonate.
 11. The introducer of claim 1, furtherincluding a needle guard adapted to cover the introducer needle.
 12. Theintroducer of claim 1, wherein the introducer is reversible.
 13. Amethod of introducing a cannula for subcutaneous administration of fluidinto a patient, comprising: inserting an introducer needle of anintroducer and a cannula into a insertion site on a patient, wherein theintroducer includes: the introducer needle; and a first arm having afirst groove adapted to slide on a first guide rail of a cannula housingand a second arm having a second groove adapted to slide on a secondguide rail of the cannula housing, wherein the cannula is mounted on acannula housing and is in fluid communication with a fluid passagewayinside a projection on the cannula housing, and wherein the first guiderail and the second guide rail are each on the projection, and whereinthe introducer is connected to the cannula housing such that theintroducer needle extends through the cannula; and disconnecting theintroducer from the cannula housing, whereby the introducer needle isremoved from the cannula.